Voyager 1 is the second-longest operating spacecraft in human history, losing out only to Voyager 2 which launched a few weeks earlier in 1977.*
The spacecraft has traveled further than any human-made object, crossing the heliopause and heading into interstellar space. While doing this, it has continued to send back useful data to Earth, helping us learn about the space between stars outside of our own Solar System. All this, while working with just 69.63 kilobytes of memory, about the size of an average JPEG, and running partly on code written in archaic computer language Fortran 5.
With such a mission, you'd expect the occasional challenge, even before you take into account the high radiation environment it is heading through. And glitches most definitely have occurred, including mysterious telemetry data that was sent back last year, likely the result of the data passing through an old onboard computer which had not been functional for years.
That was fixed in August 2022, but now there is a new problem, and it's a frustrating one.
"The spacecraft is receiving and executing commands sent from Earth; however, the [flight data system] is not communicating properly with one of the probe’s subsystems, called the telecommunications unit (TMU)," NASA explained in a statement. "As a result, no science or engineering data is being sent back to Earth."
Instead of sending back the usual varied data packages in binary code, the TMU has begun "transmitting a repeating pattern of ones and zeros as if it were 'stuck'." NASA believes the source of the problem is the flight data system, and last weekend attempted to reset the computer to the state it was in before the error occurred. However, the spacecraft has continued to send unusable data. The team will continue to work on solutions, before the painstaking 45-hour wait to find out if it worked.
"Finding solutions to challenges the probes encounter often entails consulting original, decades-old documents written by engineers who didn’t anticipate the issues that are arising today," NASA added. "As a result, it takes time for the team to understand how a new command will affect the spacecraft’s operations in order to avoid unintended consequences."
*The answer to your inevitable question of "why was Voyager 2 launched first" is that Voyager 1 was on a faster route to its planetary targets, and so was given the honor of the 1.